1. Field
The present invention relates to a wireless communication system, and more particularly to an apparatus and a method for transmitting a reference signal in a wireless communication system.
2. Discussion of the Background
With the progress of communication systems, consumers such as companies and individuals have used a wide variety of wireless terminals.
In current mobile communication systems, as a high-speed and high-capacity communication system capable of transmitting and receiving various data such as images and wireless data beyond voice-oriented services, it is required to develop a technology capable of transmitting a large amount of data coming close to that of a wired communication network. In addition, an appropriate error detection scheme in which system performance can be improved by minimizing information loss and increasing system transmission efficiency, becomes an essential element.
Also, in several current communication systems, various reference signals are used to provide information on a communication environment and the like to a counterpart apparatus in uplink or downlink.
For example, in an LTE (Long Term Evolution) system which is one of several mobile communication methods, during uplink transmission, a user equipment (UE) transmits a sounding reference signal corresponding to a channel estimation reference signal indicating a channel state of the UE to a base station apparatus. Also, during downlink transmission, in order to recognize channel information, the base station apparatus transmits a Cell-specific Reference Signal (CRS) corresponding to a reference signal to the UE in every subframe.
Meanwhile, it is usual that reference signals for this channel estimation and the like are periodically generated by an apparatus for transmitting a reference signal (for example, the UE in the case of an uplink reference signal, and the base station apparatus in the case of a downlink reference signal) and are then transmitted to an apparatus for receiving a reference signal.
Also, up to the present, such a channel estimation reference signal in uplink is generated in such a manner as to generate multiple sequences by changing a phase of an input signal in a conjugated manner by using a predetermined cyclic shift.
However, recently, due to the flexibility and the like of a communication system, there is a rising demand which is intended to further extend a channel estimation reference signal or a channel estimation sequence and use the extended channel estimation reference signal or the extended channel estimation sequence.